Ilok (Croatian pronunciation: [ilok]) is the easternmost town and municipality in northeastern Croatia. Located in the Syrmia region, it lies on a hill overlooking the Danube river, which forms the border with the Bačka region of Serbia. The population of the town of Ilok is 5,072, while the total municipality population is 6,767 (census 2011).[1] The town is home to a Franciscan monastery and Ilok Castle, which is a popular day trip for domestic tourists.

The area of present-day Ilok was populated since the neolithic and Bronze Ages. The Romans settled there in the 1st or 2nd century and built Cuccium, the first border fortification on the Danube. The Slavs settled here in the 6th century. The area was later ruled by the Bulgarian Empire, until it was included into the medieval Kingdom of Hungary.

In 12th and 13th centuries the market-town of Ilok was mentioned in documents under various names (Iwnlak, Vilak, Vylok, Wyhok, Wylak). At the end of the 13th century, Hungarian kings gave the Vylak castrum to the powerful Csák noble family. In the 13th and 14th centuries, Ilok was a capital of the semi-independent medieval state of Upper Syrmia ruled by Ugrin Csák.

Since 1526, the town was under Ottoman rule. During this time, it was mainly populated by Muslims. In 1566-69, Ilok had 238 Muslim and 27 Christian houses. In 1572, it had 386 Muslim, and 18 Christian houses. In 1669, the population of Ilok numbered 1,160 houses, and town possessed two mosques. It was kaza centre in Sanjak of Syrmia. Habsburg army firstly occupied Ilok in 1688, but Ottomans recaptured it in 1690. In 1697, Habsburg army definitively retook Ilok from the Ottomans and the Muslim population fled.